Broadcast: Tuesday 24th December 2013
8:00am-9:00am CST (14:00 GMT) < > « »
BBC Entertainment (Latin America)

Featuring: Matt Smith, Arthur Darvill, Karen Gillan, Elizabeth Berrington, Suranne Jones, Adrian Schiller, Michael Sheen

The Doctor follows a Time Lord distress signal to a mysterious asteroid in a Bubble Universe - could there really be another living Time Lord out there? But the asteroid hides a secret which could threaten the existence not only of the TARDIS crew, but...